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use super::{errors::InputError, range, Felt, Range, StackTopState, StarkField, ToElements};
use winter_utils::{
    collections::{vec, Vec},
    ByteWriter, Serializable,
};

mod inputs;
pub use inputs::StackInputs;

mod outputs;
pub use outputs::StackOutputs;

// CONSTANTS
// ================================================================================================

/// Index at which stack item columns start in the stack trace.
pub const STACK_TOP_OFFSET: usize = 0;

/// The number of stack registers which can be accessed by the VM directly. This is also the
/// minimum stack depth enforced by the VM.
pub const STACK_TOP_SIZE: usize = 16;

/// Location of stack top items in the stack trace.
pub const STACK_TOP_RANGE: Range<usize> = range(STACK_TOP_OFFSET, STACK_TOP_SIZE);

/// Number of bookkeeping and helper columns in the stack trace.
pub const NUM_STACK_HELPER_COLS: usize = 3;

/// Index of the b0 helper column in the stack trace. This column holds the current stack depth.
pub const B0_COL_IDX: usize = STACK_TOP_RANGE.end;

/// Index of the b1 helper column in the stack trace. This column holds the address of the top
/// item in the stack overflow table.
pub const B1_COL_IDX: usize = STACK_TOP_RANGE.end + 1;

/// Index of the h0 helper column in the stack trace. This column contains 1 / (b0 - 16) when
/// b0 != 16, and ZERO otherwise.
pub const H0_COL_IDX: usize = STACK_TOP_RANGE.end + 2;